YOU SAID:

It's not the best idea to use Google Translate to translate Japanese, as it often gets the grammar really wrong, mixing things up.

INTO JAPANESE

なることしばしば文法本当に間違っている、混合物日本語を翻訳する Google 翻訳を使用する最高のアイデアじゃないです。

BACK INTO ENGLISH

Be mixed, wrong grammar really often that ones is not the best idea to use Google translate to translate Japan.